Move the common plugin scanning dir stuff to be based on lws_dir, which
already builds for windows. Previously this was done via dirent for unix
and libuv for windows.
Reduce the dl plat stuff to just wrap instantiation and destruction of
dynlibs, establish common code in lib/misc/dir.c for plugin scanning
itself.
Migrate the libuv windows dl stuff to windows-plugins.c, so that he's
available even if later libuv loop support becomes and event lib plugin.
Remove the existing api exports scheme for plugins, just export a const struct
now which has a fixed header type but then whatever you want afterwards depending
on the class / purpose of the plugin. Place a "class" string in the header so
there can be different kinds of plugins implying different types exported.
Make the plugin apis public and add support for filter by class string, and
per instantation / destruction callbacks so the subclassed header type can
do its thing for the plugin class. The user provides a linked-list base
for his class of plugins, so he can manage them completely separately and
in user code / user export types.
Rip out some last hangers-on from generic sessions / tables.
This is all aimed at making the plugins support general enough so it can
provide event lib plugins later.
Add a minimal example showing how to write a binance client using
permessage_deflate and LCCSF_PRIORITIZE_READS to minimize latency.
This is partly informed by kutoga's example on
https://github.com/warmcat/libwebsockets/issues/2019 which was in
turn based on the existing ws client minimal example.
mbedtls has older and newer hashing apis, if we detected the newer ones
we use them like the older ones since generally, hashing doesn't have a
way to fail for sha and md5 update etc.
Coverity objects... change it to dumbly check the retcode.
Coverity sees we sometimes check if header length is 0 and extrapolates
from that not checking header length return is a violation. But often
we are OK if the header length is 0 and there is no error return to
check from that.
It also doesn't understand that if we saw a nonzero length for a header,
then we are going to get a non-null simple_ptr() return for sure. Just
give up and explicitly, unneccessarily check everything so coverity can
stop telling us about it.
